Switch control circuits



May 2, 1939. c. M. HINES SWITCH CONTROL CIRCUITS 'Ffiled Sept. 27, 1958 l I I I IN NTOR Clem mar.

HIS ATTORNEY I Patented May 2, 1939 UNITED STATES PATENT OFFHQE SWITCH CONTROL CIRCUITS Application September 27, 1938, Serial No. 231,886

9 Claims.

My invention relates to an improved control system for the motor for operating a railway track switch, and particularly to improved means for providing overload protection for the switch motor.

It has heretofore been proposed to provide an overload relay having a pickup winding energized in accordance with the value of the current taken by the motor for operating a railway track 10 switch, this relay being arranged so that in the event the motor current is excessive the relay contacts will become picked up, thereby interrupting the circuit for energizing the switch motor and thus preventing possible injury to the motor.

It has also been proposed heretofore to provide means operative on picking up of the overload relay contacts to energize a holding winding for the relay from a source in the vicinity of the switch, as for instance the battery from which current is supplied to operate the switch motor. The overload relay holding winding when energized maintains the contacts of the relay picked up and thereby maintains the switch motor circuit interrupted, while means is provided which is operative on reversal of the position of the switch control lever for controlling energization of the holding winding of the overload relay to effect the release of the relay contacts and thus reestablish the energizing circuit for the switch motor.

It is essential to provide means for controlling the polarity of the current supplied to the overload relay holding winding so that it will be varied in accordance with the direction of energization of the pick-up winding of the relay.

It is an object of my invention to provide a switch control system of the type described and incorporating means controlled by the polarize switch control relay for controlling the polarity of the current supplied to the holding winding of the overload relay.

A. further object of my invention is to provide an improved control system of the type described in which the polarized switch control relay controls the polarity of the current supplied to the overload relay holding winding without necessitating the use of a relay separate from the control relay.

Another object of my invention is to provide an improved switch control system in which on picking up of the contacts of the overload relay they will remain picked up until the switch 55 control lever is moved from one position to the other, whereupon the relay contacts become released and restore control of the switch to the operator.

A further object of my invention is to provide an improved switch control system.

Other objects of my invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawing.

In the drawing the single figure is a diagram 9 illustrating one embodiment of the improved switch control system provided by my invention.

Referring to the drawing, the reference character W designates a railway track switch which is operated by the well-known dual selector type of mechanism. In the form here shown diagrammatically, this mechanism includes a dual selector lever S which operates a link 3. When the lever S is in the normal position as shown in the drawing, link 3 connects switch W with motor M, while when the selector lever S is in the reverse position, link 3 no longer connects switch W to motor M, but instead connects the switch to a hand-throw lever H.

The switch W operates a. motor cut-out contact 5 in accordance with the position of the switch. The contact 5 is arranged so that it engages a stationary contact 6 in all positions of the switch W except the reverse position thereof, while the contact 5 engages a stationary contact I in all positions of the switch W except the normal position thereof.

The selector lever S operates contacts 9 and ill in accordance with the position occupied by the lever. Then the lever S is in the normal position as shown, contact 9 is out of engagement with stationary contacts H and [2, while the contact it engages stationary contacts M and Hi. When the lever S is in the reverse or handthrow position, the contact In no longer engages contacts I land I5, while contact 9 engages contacts and I2.

The motor M is provided with an armature 45 I6 and a field winding ll, while a polarized relay WR is provided for controlling the circuits for energizing the motor M. In addition, an overload relay OR is provided and is responsive to the current taken by the motor M.

The polarized switch control relay WR is controlled by a switch control lever L which is located at a point remote from the switch. The lever D has associated therewith contacts 19 and 20 to which are connected control wires 2! and 22. When the lever L is in the normal position as shown in the drawing, contact l9 connects control wire 2| to terminal B of battery 25, and contact 20 connects control wire 22 to terminal C of battery 25. When the lever L is in the reverse position, contact |9 connects control wire 2| to terminal C of battery 25;

while contact 20 connects control wire 22 to terminal B of battery 25.

Control wire 2| is connected to contact 28 of overload relay OR, and is connected through an asymmetric unit 30 to reverse polar contact 3| of switch control relay WR. Control wire 2| is also connected through an asymmetric unit 33 to normal polar contact 35 of relay WR. The

asymmetric units 30 and 33 are arranged so that one of these units will permit flow of current or one relative polarity, and the other will permit flow of current of the opposite relative polarity.

Control wire 22 is connected to one terminal of the winding of the relay WR, while the other terminal of this winding is connected by a wire 37 to a polar contact 38 of relay WR, and also to a movable contact 40 of relay OR. The contact 40 when released engages contact 28 to which is connected control wire 2| so that when the contact 4|] of overload relay OR is released, a circuit is established to energize the winding of control relay WR from the control wires 2| and 22. This circuit includes control wire 2|, contacts 2840 of overload relay OR, wire 37, winding of relay WR and control wire 22.

The control relay WR has a plurality of neutral contacts 42 which are connected by wire 44 to terminal B of battery 45, while a branch of the wire 44 is connected to a reverse polar contact 46 of relay WR.

The movable contacts 42 when picked up engage stationary contacts 41 which are connected by a wire 49 to a normal polar contact 5|] and a reverse polar contact 5| of the relay WR.

The relay WR has a polar contact 53 which is connected by a wire 54 to one brush of the motor armature IS. The polar contact 53 is adapted to engage the normal polar contact 5|], and to also engage" the reverse polar contact 56 which is connected by a wire 51 to contact 6 associated with the switch operated contact 5.

The relay WRhas, in addition, a polar contact 59 which at times engages the reverse polar contact 5|, and at other times engages the normal polar contact 6| which is connected'by a wire 62 to stationary contact 1 associated with the switch operated contact 5.

The polar contact 59 is connected by a wire 64 to one terminal of a resistor 65 and of the pickup winding 66 of overload relay OR. The other terminals of the resistor 65 and of the relay pick-up winding 66 are connected by a wire 61 i to a brush of the motor armature IS.

The resistor 65 has a positive thermal coefficient of resistance, that is, the resistance of the resistor increases as the temperature of the material of which it is constructed increases. Accordingly, on an increase in the temperature of this unit there is a reduction in the flow of current through the resistor and a corresponding increase in the flow of current in the pick-up Winding 66.

The resistor 65 and the relay pick-up winding 66 are arranged and proportioned so that on normal flow of current in the circuit of the switch motor M insufiicient current flows in the pick-up winding I56 to eiiect picking up of the relay contacts. However, on an abnormal flow of current in the circuit of the motor M for an unusual period of time, the resistor 65 becomes heated and efiects an increase in the flow of current in the pick-up winding 66 sufficient to effect picking up of the relay contacts.

The relay WR has a polar contact 10 which is connected by a wire H to one terminal of the holding winding 12 of the overload relay OR, While a branch of the wire 12 is connected to contact l4 associated with the selector lever contact ill. The contact H1 at times engages the reverse polar contact 46 to which is connected a branch of wire 44 leading from terminal B of battery 45, and at other times engages a stationary contact 14 which is connected by a wire 15 to terminalN of battery 45.

One terminal of the motor field winding I! is connected to wire 15 and thereby to terminal N of battery 45, while the other terminal of the field winding I! is connected to switch operated contact 5.

The overload relay OR has a movable contact H which is connected by a wire 18 to one terminal of the holding winding 12 of the relay OR, while a branch of this wire is connected to stationary contact I2 which at times is engaged by selector lever contact 9. The contact 11 when released engages a stationary contact 19 which is connected by a wire to contact |5 which in the normal position of the selector lever S is engaged by the contact I0.

It will be seen that when the selector lever S is in the normal position and the contacts of relay OR are released, a shunt circuit is established for the holding winding 12 of overload relay OR. This circuit is traced from one terminal of the winding 12 through wire 18, contacts ll-l9, wire 80, contacts |5--|0|4, and wire H to the other terminal of the relay winding. This shunting of the holding winding serves to render the overload relay OR slow in picking up and prevents unintended picking up of the relay contacts on a momentary overload of the switch motor.

The contact 11 of relay OR when picked up engages a stationary contact 82 to which is connected wire 84 leading from terminal C of battery 45. A branch of wire 84 is connected to stationary contact II which at times is engaged by the contact 9.

The relay OR, has a movable contact 86 which becomes picked up when the contact 11 is picked up. The contact 86 is arranged so that it does not engage the contact 40 until the contact 11 engages contact 82, and therefore does not move contact 40 out of engagement with stationary contact 28 to interrupt the circuit of the winding of the relay WR until contact 11 is moved into engagement with contact 82 to establish a circuit for energizing the holding winding 12 of relay OR. i

It will be seen, therefore, that on picking up of the contacts of the overload relay OR a circuit for energizing the holdingwinding 12 is established before the circuit for the winding of the relay'WR is interrupted and the neutral contacts 42 of relay .WR become released to interrupt the circuit for energizing the switch motor M.

positionwhich it assumes when the switch W,

the switch control lever L, andthe dual selector lever Sarein'their normalpositions, and when The equipment is shown in the drawing in the l the contacts of the overload relay OR are released.

At this time as the control lever L is in the normal position, the contacts I9 and 20 effect the supply of current of normal relative polarity from the battery 25 to the control wires 2| and 22, and as the contacts of the overload relay OR are released, a circuit is established to energize the winding of the polarized switch control .relay WR with this current. This circuit includes wire 2|, contacts 28-40 of overload relay OR, wire 31, winding of relay WR and control wire 22.

As the winding of relay WR is energized, the neutral contacts 42 of this relay are picked up, while the polar contacts of the relay are in their normal positions as shown. At this time, however, the circuit for energizing the motor M is interrupted as the switch operated contact 5 is out of engagement with stationary contact 1. The motor M, therefore, is not energized and the switch W remains in the normal position.

If at this time the operator wishes to effect movement of the switch W from the normal to the reverse position, he may do so by moving the control lever L from its normal to its reverse position. On this movement of the control lever L the contacts i9 and 20 interrupt the supply of current of normal relative polarity to the control wires 2| and 22 and effect the supply of current of reverse relative polarity thereto. On this reversal of the polarity of the current supplied to the control wires 2| and 22 there is a reversal in the direction of energization of the winding of the relay WR with the result that the neutral contacts 42 of this relay become released and then pick up, while the polar contacts of this relay are shifted from their normal to their reverse positions.

On movement of the polar contacts 53 and 59 of relay WR from their normal to their reverse positions a circuit is established toenergize the switch motor M with current supplied from the battery 45. This circuit is traced from terminal B of battery 45 through wire 44, neutral contacts 424'| of relay WR, wire 49, reverse polar contacts 5|59 of relay WR, wire 64, resistor 65 and holding winding 66 of relay OR in parallel, wire 51, motor armature l6, wire 54, reverse polar contacts 53-55 of relay WR, wire 51, switch contacts 65, motor field winding ll and terminal N of battery 45. As a result of this energization of the switch motor M, the motor is caused to drive the switch W from the normal to the reverse position, and when the switch reaches the reverse position, switch operated contact 5 is moved out of engagement with contact 6 to thereby interrupt the circuit for energizing the switch motor M.

In similar manner, if when the switch W is in the reverse position the operator wishes to effect movement of the switch to the normal position, he may do so by moving the control lever L from its reverse to its normal position. As a result of this movement of the control lever L, current of normal relative polarity is supplied to the control wires 2| and 22 and the polar contacts of the relay WR are shifted from their reverse to their normal positions, thereby establishing a circuit for energizing the switch motor in a direction to effect movement of the switch from the reverse to the normal position.

The circuit for energizing the switch motor M includes terminal B of battery 45, wire 44, neutral contacts 42-4l of relay WR, normal polar contacts 55-53 of relay WR, wire 54, motor armature l6, wire 61, resistor 65 and pick-up winding 66 of relay OR in parallel, normal polar contacts 59-6| of relay WR, wire 52, switch contacts 1-5, field winding ll and terminal N of battery 45.

When the switch W attains the normal position, contact 5 is moved out of engagement with contact 1, thereby interrupting the circuit for energizing the switch motor M.

This system is arranged so that in the event that during movement of the switch W from one of its positions to the other, movement of the switch is obstructed before the switch reaches the position to which it is being moved, the contacts of the overload relay OR will become picked up and will cause the circuit of the switch motor M to be interrupted and thus prevent injury to the switch motor.

For purposes of illustration, it will be assumed that the switch W is being moved from the normal to the reverse position and that movement of the switch is obstructed before the switch reaches the reverse position. In order to efiect this movement of the switch to the reverse position, the control lever L is moved from its normal to its reverse position, thereby effecting the supply of current of reverse relative polarity to the control wires 2| and 22. On the supply of current of this polarity to the winding of the relay WR the polar contacts of this relay are shifted from their normal to their reverse positions, thereby establishing the previously traced circuit to energize the switch motor M in a direction to cause the motor to move the switch W from the normal to the reverse position.

On the occurrence of the obstruction to movement of the switch there is an unusually large flow of current in the circuit of the switch motor and the resistance unit 65 becomes heated, thereby increasing its resistance and increasing the flow of current in the pick-up winding 66 of the relay OR. As a result of this increased current flow in the pick-up winding 66 the contacts of the relay OR become picked up and contact 1! is moved out of engagement with contact 19 to interrupt the shunt circuit for the holding winding 12, while contact 11 is moved into engagementswith contact 82 to establish a circuit for energizing the holding winding 12. This circuit is traced from terminal C of battery 45 through wire 84, contacts 82-|| of relay OR, wire 18, holding winding 12, wire reverse polar contacts 10-46 of relay WR, and wire 44 to terminal B of battery 45. As the holding winding 72 is energized, the contacts of the relay OR remain picked up after interruption of the switch motor circuit. The various parts of the system are arranged so that the force developed on this energization of the holding winding 12 assists that developed by energization of the pick-up winding 56 of relay OR.

In addition, on picking up of the contacts of relay OR, contact 86 engages contact 40 and moves it away from contact 28, thereby interrupting the circuit of the winding of the relay WR. As previously explained, however, contact 4|! is not moved out of engagement with con tact 28 until after contact 11 engages contact 82 to establish the circuit for the holding winding of the relay OR.

On movement of contact 4?) out of engagement with contact 28 the connection between control wire 2| and wire 31 leading to a terminal of the winding of relay WR is interrupted. At this time polar contact 38 of relay WR engages reverse polar contact 3!. Polar contact 38 has connected thereto wire 31, while wire 2| is connected ric. unit 38 to energize the winding of the relay WR. Accordingly, on picking up of the contacts of the overload relay OR the circuit for energizing the winding of the switch control relay WR is interrupted and the neutral contacts 42 of this relay become released and interrupt the circuit for energizing the switch motor M. The internal construction of the relay WR. is such that on interruption of the circuit for energizing the winding of the relay, the polar contacts of the relay remain in their last operated position and hence remain in engagement with the reverse polar contacts. a

As previously explained, on picking up of th contacts of the overload relay OR, the contact l"! establishes a circuit for energizing the holding winding 12 of the relay OR so that the relay contacts when picked up remain picked up.

This control system is arranged so that after picking up of the contacts of the overload relay OR and resultant interruption of the switch motor circuit, the operator may effect energization of the switch motor M to return the switch W tothe position from which it was being moved at the time movement of the switch was preyented. I

In order to efiect this control of the switch motor the control lever L is returned .to its normal position, thereby interrupting the supply of current of reverse relative polarity to the control wires 2| and 22 and eifecting the supply of current of normal relative polarity to the control wires.

On the supply of current of normal relative polarity to the control wires 2| and 22 at a time when the polar contacts of the relay WE are in their reverse positions, current is supplied to energize the winding of the relay WR by way of a circuit which includes control wire 2l asym-. metric unit 3!), reverse polar contacts 3l..38 of relay WR, wire 37, winding of relay WR and control wire 22. As previously, explained, the asymmetric unit is poled topermit flow of current of normal relative polarity, and hence on the supply of current of this polarity to the control wires current is supplied to energize the winding out of engagement with contact 3| and into engagement with contact 35.

' On movement of the contact 38 out of engagement with contact 3! and into engagement with contact the supply of current to the winding of the relay WR through asymmetric unit 39 is out oif, while current of normal relative polarity supplied to the control wires 2i and 22 cannot flow through the asymmetric unit 33. Accordingly the supply of current to the winding of the relay WR through the circuit including the polar contact 38 is cut off.

On movement of the polar contacts of the relay WR from their reverse to their normal positions the contact IE3 is moved out of engagement with reverse: polar contact 46 and intoengagement with normal polar contact 14. On

movement of the contact 70 out of engagement with contact 46 the connection from wire 1|, leading from one terminal of the winding of the relay OR, to wire 44, leading to terminal B of battery 45 is interrupted, while on movement of contact :70 into engagement with contact '14 a circuit is established to connect wire H to wire 75 leading to terminal N of battery 45. It will be seen, therefore, that on this movement of the polar contact is of relayWR. there is a reversal in the direction of energization of. the holding winding 12 of relay OR. As a result, the contacts of the relay OR become released, and contact 17 moves out of engagement with contact 82, thereby interrupting the circuit for energizing the holding winding 12 with the result that when the contacts of the relay become released, they will not thereafter becomepicked up.

In addition, on the release of the contacts of the relay OR contact 85 permits contact 40 to engage contact 28 to again establish connection between control wire 2i. and wire 3? leading to the one terminal of the winding of the relay WR. The winding of relay WR, therefore, is energized with current of normal relative polarity and the polar contacts of the relay remain in, their nor-,.

mal positions, while the neutral contacts 42 of the relay are picked up and establish the previously traced circuit for energizing the switch motor M Ma direction to effect movement of the switch W away from the reverse position to the normal position. When the switch W attains the normal position, the switch contact 5 is moved tion, theoverloaol relay OR will operate to interrupt the circuit for energizing the win-dingof the control relay WR. and the contacts 42 of the relay WR will become released to interrupt the circuit for energizing the switch motor M.

When the switch is being moved from the reverse to the normal position, the polar contacts of the relay WE are ,in their normal positions as shown with the result that a circuit is established from wire "H, leading from one terminal of the winding 12 of relay OR, to wire l5 leading to terminal Nof battery 45. of contact 11 of relay OR a circuit is established from terminal C of battery 45 to wire 78 leading to the other terminal of the holding winding 12 of relay OR. It will be seen that when the polar contacts of relay WR. are in their normal positions the winding 12 is energized with cur,- rent of a polarity opposite to that with which it is energized when the polar contacts of the relay WR. are in their reverse positions.

on picking up of the contacts of the relay OR contact 40 is moved out of engagementwith conthis timepolar contact'38 is in engagement with" normal polar contact 35, but the asymmetric unit 33 is poled to prevent flow of current of normal On picking up relative polarity from wire 2! to wire 31 and no current is supplied through the unit 33 to energize the winding of the relay WR. Accordingly the neutral contacts 42 of the relay WR be'come released on picking up of the contacts of the ovenoau relay R.

If after picking up of the contacts of the overload relay OR the operator wishes to effect return of the switch to the reverse position, that is, to the position from which it was being moved at the time movement of the switch was obstructed, he may do so by returning the control lever L to the reverse position. This movement of the control lever effects the supply of current of reverse relative polarity to the control wires 2| and 22. The asymmetric unit 33 is arranged to permit flow of current of this relative polarity between wires 3'! and 2| and accordingly current is supplied to energize the winding of the relay WR. On energization of the Winding of the relay WR the polar contacts of this relay are shifted from their normal to their reverse position. As previously explained, on movement of contact 38 out of engagement with contact 35 the energizing circuit for the winding of relay WR is interrupted, but the internal construction of the relay is such that once movement of the polar contacts is initiated, the contacts will continue their movement until they have completed their movement to the other position. When contact 38 is moved into engagement with contact 3!, no current is supplied through the asymmetric unit 39 as the unit 39 is arranged to prevent flow of current of reverse relative polarity between the wires 2| and 31.

On movement of polar contact 10 out of engagement with contact 14 the circuit from wire 7 I, leading from one terminal of the holding winding 12 of relay OR, to wire 15, leading to terminal N of battery 45 is interrupted, while on movement of contact 70 into engagement with contact 46 the wire II is connected to wire 44 leading to terminal B of battery 45. It will be seen, therefore, that on this change in the position of the polar contacts of the relay WR there is a reversal in the direction of energization of the holding winding 12 of relay OR, and the contacts of the relay OR become released and contact 'l'l interrupts the circuit for energizing the holding winding 12 so that the contacts of the relay do not thereafter again become picked up.

Similarly, contact 86 permits contact 40 to engage contact 28 to establish a circuit from wire 2| to wire 31 so that the winding of the relay WR is again energized by current supplied from the control wires 2| and 22. The neutral contacts of the relay WR, therefore, become picked up and complete the circuit to energize the switch motor M and cause the motor M to move the switch W to the reverse position.

From the foregoing, it will be seen that this switch control system is arranged so that on picking up of the contacts of the overload relay OR the circuit for energizing the polarized switch control relay WR is interrupted to thereby interrupt the energizing circuit for the switch motor. In addition, it will be seen that when the polar contacts of the relay WR are in either position, a circuit independent of the overload relay is established to permit energization of the winding of the relay WR with current only of a polarity effective to cause movement of the polar contacts of the relay to their other positions, and that on this movement of the relay polar contacts, the

polarity of the current supplied to the holding winding of the overload relay is reversed to thereby eilect release of the contacts of the overload relay. On this release of the overload relay contacts the circuit for energizing the winding of the polarized switch control relay from the control wires is reestablished so that this relay completes the energizing circuit for the switch motor, while the polarized switch control relay may thereafter be controlled in the usual manner.

This system is also arranged so that on movement of the selector lever S to the hand-throw position the holding winding of the overload relay OR is energized so that the contacts of the overload relay become picked up and effect deenergization of the switch control relay and thus prevent energization of the switch motor as long as the selector lever S remains in the hand-throw position,

Furthermore this system is arranged so that on subsequent return of the selector lever S from the hand-throw position to the normal position the holding winding of the overload relay will .continue to be energized until there is a change in the position of the switch control relay, whereupon the holding winding of the overload relay will become deenergized.

On movement of the selector lever S from the normal position to the hand-throw position, the contact I0 is moved out of engagement with thecontacts l4 and I5, thereby interrupting the shunt circuit for the holding winding 120i relay OR, while contact 9 is moved into engagement with contacts Ii and i2 and completes a circuit from terminal C of battery 45 to wire 78 leading to one terminal of the winding 12. The other terminal of the winding 12 is connected by polar contact 10 of relay WR either to wire 15, leading to terminal N of battery 45, or to wire 4 1 leading to terminal B of battery 45, depending upon the position occupied by the contact 70.

As the holding winding 12 of relay OR is energized, the contacts of relay OR are picked up and contact 40 is held out of engagement with contact 28 to thereby interrupt the circuit from control wire 2| to Wire 3'! leading to a terminal of the winding of relay WR, while contact ll engages contact 82 to establish a stick circuit for the holding winding 12.

It will be seen that as the contacts of relay OR are picked up at a time when the selector lever S is in the hand-throw position, the circuit for energizing the winding of the switch control relay WR is interrupted, and the neutral contacts 42 of this relay are released. Accordingly the circuit for energizing the switch motor M is interrupted and will be maintained interrupted as long as the contacts of relay WE are released.

On subsequent return of the selector lever S from the hand-throw position to the normal position contact 9 is moved out of engagement with contacts I l and I2, while contact I0 is again moved into engagement with contacts l4 and I5. On movement of contact 9 out of engagement with contacts II and I2 the connection established by contact 9 between wire 84, leading from terminal C of battery 45, to wire 18, leading to a terminal of holding winding 12 is interrupted, but the circuit for energizing the winding 12 is maintained by contact 11 which is picked up at this time.

On movement of contact lfl into engagement with contacts l4 and I5 wire H is connected to Wire 80, but the shunt circuit for the holding winding 12 is not complete as contact 1! is picked up.

If the operator Wishes to regain control of the switch after movement of the selector lever S to the normal position, he may do so by moving the switch control leverLto a difierent position, thereby effecting reversal of the polarity of the current supplied to the control wires 2| and 22. On this reversal of the polarity of the current supplied to the control wires current is supplied to a circuit previously explained in detail, and the contacts of this relay thereupon become released and reestablish the circuit for energizing the winding of the switch control relay WR. from the control wires 2| and 22.

Although I have herein shown and described only one form of apparatus embodying myinvene tion, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, What I claim is:

1. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for moving said switch, a pair of conductors, means for supplying current of one or the, other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, an overload relay having a winding energized in accordance with the current taken by the switch motor, said overload relay having contacts which become picked up when the current taken by the switch motor exceeds a predetermined value, a circuit controlled by a contact of the overload relay for energizing the winding of the polarized relay from said pair of conductors, and circuits independent of the overload relay contacts and controlled by a polar contact of the polarized relay for also energizing the winding of the polarized relay from said pair of conductors.

2. ma switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for moving said switch, a pair of conductors, means for'supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, said polarized relay having a polar contact movable between a normal and a reverse position in accordance with the polarity ofthe current suppliedto the relay winding, an overload relay having a contact which becomes picked up when the current taken by the relay is in the reverse position and through which currentv of normal polarity only may be supplied from said conductors to the winding of the polarized relay.

3. In a switch control system, in combination, a railway trackswitch movable between a normal and a reverse" position, a mot-or for moving said switch, a pair of conductors, means for supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, an overload relay having a pick-up winding energized in accordance with the magnitude of the current taken by theswitch motor, said overload relay also having a holding winding, the overload relay having contacts which become picked up on a predetermined increase in the magnitude of the current supplied to the pick-up winding or when the holding winding is energized, a circuit controlled by a contact of the overload relay for energizing the winding of the polarized relay from said conductors, and circuits independent of the contacts of the overload relay and controlled by a polar contact of the polarized relay for also energizing the winding of the polarized relay from said conductors, a contact of the overload relay being operative when picked up to establish a control circuit through which current may be supplied to the holding winding of the overload relay, a polar contact of the poralized relay controlling the, polarity of the current supplied to said control circuit.

4. In a switch control system, in combination, a railway track switch movable between a nor- ,mal and a reverse position, a motor formoving said switch, a pairof conductors, means for supplying current of one or the other polarity to said conductors, a polarized, relay controlling circuits for energizing the switch motor, said polarizedlrelay having polar contacts movable between a normal and a reverse position in accordance with the polarity of the current supplied to the relay winding, an overload relay having a pick-up winding and a holding winding, means for energizing the pick-up; winding in accordance with the magnitude of the current taken by the switch motor, the overload relay having contacts which become picked up on a predetermined increase in themagnitude of the current supplied to the pick-up winding or when the holding winding is energized, a circuit controlled by a contact of the overload relay for energizing the winding of the polarized relay from said conductors, a circuit which iscomplete only when the polar contacts of the polarized relay are in their normal position and through which current of reverse polarity only may be supplied from said conductors to the winding of the polarizedrelay, and a circuit which is complete only when the polar contacts of the polarized relay are in their reverse positions and through which current of normal relativepolarity onlymay be supplied tothe "winding Of the polarized relay, acontact of the overload relay being operative H ,when picked up'Yto establish a, control circuit through which current, maybe, supplied as the overload relay holding winding, a polar contact of the polarized relay controlling the polarity of the current supplied to said control circuit.

5. In a switch control system, in combination, a railway track switch movable between a normal and a reverseposition, a'motor for moving said'switch, a pair of conductors, means for supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, said polarized relay having a polar contact movable 16 between a normal and a reverse position in accordance with the polarity of the current supplied to the relay winding, an overload relay having a winding energized in accordance with the magnitude of the current taken by the switch motor and having a contact which becomes picked up when the current taken by the switch motor exceeds a predetermined value, a circuit controlled by the contact of the overload relay for energizing the winding of the polarized relay from said conductors, a first circuit which is established when the polar contacts of the polarized relay are in their normal positions and through which current may be supplied from said conductors to energize the winding of the polarized relay, and a second circuit which is established when the polar contacts of the polarized relay are in their reverse positions and through which current may be supplied from said conductors to energize the winding of the polarized relay, said first and second circuits each having connected in series therewith an asymmetric unit arranged to permit fiow of current of a polarity effective to cause movement of the relay contacts away from the position in which the contacts complete the circuit including such asymmetric unit.

6. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for moving said switch, a pair of conductors, means for supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, an overload relay having a pick-up winding and a holding winding, means for energizing the pick-up winding in accordance with the magnitude of the current taken by the switch motor, the overloadrelay having contacts which are normally released and which become picked up when the current taken by the switch motor exceeds a predetermined value or when the holding winding is energized, the overload relay contacts when released establishing a circuit for energizing the winding of the polarized relay from said pair of conductors, the overload relay contacts being operative on movement to their picked-up position to first establish a control circuit for energizing the holding winding of the overload relay and to thereafter interrupt the circuit for energizing the winding of the polarized relay from said pair of conductors.

7. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for moving said switch, a pair of conductors, means for supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, an overload relay having a pick-up winding and a holding winding, means for energizing the pick-up winding in accordance with the magnitude of the current taken by the switch motor, the overload relay having contacts which are normally released and which become picked up when the current taken by the switch motor exceeds a predetermined value or when the holding winding is energized, the overload relay contacts when released establishing a circuit for energizing the winding of the polarized relay from said pair of conductors, the overload relay contacts being operative on movement to their picked-up position to first establish a control circuit for energizing the holding winding of the overload relay and to thereafter interrupt the circuit for energizing the winding of the polarized relay from said pair of conductors, and means controlled by a polar contact of said polar relay for controlling the polarity of the current supplied to said control circuit.

8. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for moving said switch, a pair of conductors, means for supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, an overload relay having a pick-up winding and a holding winding, means for energizing the pick-up winding in accordance with the magnitude of the current taken by the switch motor, the overload relay having contacts which are normally released and which become picked up when the current taken by the switch motor exceeds a predetermined value or when the holding winding is energized, the overload relay contacts when released establishing a circuit for energizing the Winding of the polarized relay from said pair of conductors, the overload relay contacts being operative on movement to their picked-up position to first establish a control circuit for energizing the holding winding of the overload relay and to thereafter interrupt the circuit for energizing the winding of the polarized relay from said pair of conductors, a first circuit controlled by a polar contact of the polarized relay and through which current may be supplied from the said conductors to the winding of the polarized relay, said circuit being complete when and only when the polar contact is in its norm-a1 position and being adapted to permit flow of current only of a polarity effective to cause movement of the relay polar contacts to their reverse position, a second circuit controlled by a polar contact of the polarized relay and through which current may be supplied from the said conductors to the winding of the polarized relay, said circuit being complete when and only when said polar contact is in its reverse position and being adapted to permit flow of current only; of a polarity effective to cause movement of the relay polar contacts to their normal position.

9. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for moving said switch, a pair of conductors, means for supplying current of one or the other polarity to said conductors, a polarized relay controlling circuits for energizing the switch motor, an overload relay having a pick-up winding and a holding winding, means for energizing the pick-up winding in accordance with the magnitude of the current taken by the switch motor, the overload relay having contacts which are normally released and which become picked up when the current taken by the switch motor exceeds a predetermined value or when the holding winding is energized, the overload relay contacts when released establishing a circuit for energizing the winding of the polarized relay from said pair of conductors, the overload relay contacts being operative on movement to their picked-up position to first establish a control circuit for energizing the holding winding of the overload relay and to thereafter interrupt the circuit for energizing the Winding of the polarized relay from said pair of conductors, means controlled by a polar contact of said polar relay for controlling the polarity of the current supplied to said control circuit, a first circuit controlled by a polar contact of the polarized el y and throu h which current may be supplied from said conductors to the winding of the which current may be supplied fr m the said conductors to the winding of the polarized relay, said circuit being complete when and only when said polar contact is in its reverse position and being adapted to permit flow of current only of a 5 polarity effective to cause movement of the relay polar contacts to their normal position.

CLAUDE HINES. 

